Hi Michael, If packets would get mixed up, in my view the "call id's" should be mixed up too, and this should be noticeable in the logs. Perhaps you could enable the debugging and post the results of kern.log together with 2 tcpdumps of both external and internal interfaces: tcpdump -i eth0 -vvv -xx -s 0 ip host ip_addr_pptp_server > tcpdump-2.6.10+pptp+testcase-eth0.txt tcpdump -i eth1 -vvv -xx -s 0 ip host ip_addr_pptp_server > tcpdump-2.6.10+pptp+testcase-eth1.txt Where you should change "ip_addr_pptp_server" with the IP address to which both clients try to connect to. Please use the netfilter to bugzilla to file the bug (you can upload the logs as attachments there). This should give a complete overview of what is happening. Don't know if it is possible for you, but you could try a patched vanilla 2.6.10 kernel too, to rule out the fedora kernel has some incompatible patches for the pptp patch. Regards, Sander Eikelenboom I have a firewall which does NAT of outgoing connections. Several clients behind this box must connect to the same external PPTP server. This did work fine on a 2.4.27 kernel. However, with the newest version of the PPTP conntrack/nat helper (from SVN, Revision 3839) and Fedora Core 3 (2.6.10), this does no longer work (both clients and server are unchanged, only the firewall is replaced). It applies cleanly and I can connect to an external PPTP server from a single client: everything works fine. But as soon as a second client behind the firewall tries to connect to this server, problems occur. Either the connection does not get established (most cases), or the first connection is broken (rarely); completely working: never. It seems, that some packets get mixed up between those two connections. Is there any workaround for this or how to help the developers in resolving the problem? I have enabled all the debugging (printk), but the resulting log doesn't help (at least me). Thanks, Michael